The Oireachtas banking inquiry's final report will be issued on Wednesday - but for members it has been over a year and a half in the making.

The 11 member-committee invested hundreds of hours to hear from 128 witnesses about the events which led to the collapse of the Irish economy.

The inquiry came at a crucial time for politicians, with a general election approaching and many committee members facing battles to retain their seats.

Fianna Fáil TD Michael McGrath admits the inquiry came at a price. His other Oireachtas duties were sidelined due to the committee's heavy workload.

“This was no doubt the single biggest project that a group of Oireachtas members ever undertook,” he said.

“People often refer to the Dirt [tax] inquiry, but it didn’t last a fraction of the time the banking inquiry has lasted.”

The Cork South Central TD added: “There were consequences for the individual members and I am not sure that was entirely clear when we initially signed up for it.

‘Better structure’

“A better structure could be put in place to reflect the massive time commitment involved for the members.”

The inquiry was established in November 2014 and held its first public hearings in December 2014, concluding in July last year.

The initial part was the context phase where economists, journalists and authors of previous banking reports were asked to give evidence before the committee.

It then proceeded to the context phase where senior bankers, including former Irish Nationwide boss Michael Fingleton and former politicians including Brian Cowen and Bertie Ahern, gave their testimony.

Labour Senator Susan O'Keeffe admits the inquiry was never going to be the full picture of the economic crash.

She said: “We were always constrained by the court cases. It meant we could barely examine Anglo Irish Bank, Irish Nationwide or Permanent TSB. So this report won’t be the complete story but it will be an official record from the words of those involved and from the documents that have never been seen before.”

The committee was also restrained in its work due to the defeat of the Oireachtas inquiries referendum in 2011.

The result meant the committee could not make any findings of fact against a person.

Fine Gael Senator Michael D'Arcy said this was one of the biggest frustrations the members had.

He said: “If 80 people were in a room and 79 people agreed on what happened and one did not agree, we were disallowed from making a judgement. If everyone else said black and someone else said white, we could not use it. That is nuts, the legislation was too restrictive.”

The report, which will be released on Wednesday, will make a series of recommendations to change the Oireachtas Inquiries Act, introduced in 2013 by Minister for Public Expenditure Brendan Howlin.

Socialist TD Joe Higgins believes the inquiry was a worthwhile experience but admits the legislation was difficult to work within.

“For me the legislation was the biggest factor. I asked the questions I wanted to but I would have preferred to be able to engage a bit more vigorously with witnesses and to be able to cross-examine more vigorously.”

The committee was due to report at the end of November but was delayed due to allegations made by a whistleblower who worked with the inquiry.

The investigator made a series of claims of preferential treatment by the committee to witnesses. Senior counsel Senan Allen was appointed to investigate the allegations, who found they were unfounded.

Many mistakes

Fine Gael TD John Paul Phelan admitted there were many mistakes made along the way by the committee that extended the process unnecessarily.

He said the context phase was too long and the process was started too late in the electoral cycle.

“It should have been started sooner. It couldn’t have been started too much sooner because of the referendum. That would have meant a less frantic lead-up to the publication.”

Mr McGrath said there were too many members on the committee, causing a repetition of questions.

A draft report was prepared for the committee by its investigation team and distributed to members in November. However, it was deemed not fit for purpose and the inquiry rushed to have it completed in time.

Mr Phelan admits the committee put too much trust in the team while Ms O’Keeffe said the team was not properly equipped.

She said: “The people appointed had expertise in law and banking but there was nobody there like me - an investigative journalist, a cynic - and I think that was a fault.”

Mr Phelan added: “In hindsight the committee should have had more oversight of what was being prepared.”

The 11 members insist the inquiry was not a waste of time but say the same format should not be followed by future committees.

Two members of the inquiry, Sinn Féin TD Pearse Doherty and Mr Higgins, will not sign off on the report.

Mr Higgins will launch his own minority report in the Merrion Hotel this morning.